What’s the world come to?
In a world without Half Life, the SiN games might have had a better chance at mainstream appeal. You see, back in yonder era of the late 90’s a little developer you might know called Ritual Entertainment put out a daring first person shooter called SiN. It followed the adventures of Col. John Blade, commander of the HardCorps security forces in a world where the police have collapsed and private security have taken their place. SiN (yes, it has that strange capitalization) introduced a lot of concepts into gaming from its high-functioning AI to driving vehicles, expanding upon the non-linear level design capitalized by Build engine games like Duke 3D and Shadow Warrior, knocking weapons out of people’s hands, and location-specific damage.

It also released about 10 days before Half Life would come out and got completely tossed to the side. In 2006 Ritual Entertainment would release SiN Episodes: Emergence, the first in a series of planned episodic releases that once again broke new ground in gaming. Emergence featured things not really seen in the Source engine yet like vehicles with location-specific damage, better AI, the game reacting to what you’re looking at, and a sliding difficulty based on how well you’re playing.
Ritual Entertainment planned nine episodes for SiN Episodes, with the idea being that the game would take metrics from choices people make and future episodes would go by the canon of the majority. Think Telltale’s end-game stats but with a point. Unfortunately while Emergence would do well enough to pay for itself, it wouldn’t fund a sequel and in 2007 Ritual was bought up by Mumbo Jumbo for reasons nobody can quite explain as Mumbo Jumbo makes casual games for mobile devices.

Since then the SiN property has been kicked around with nobody sure of where it is headed. There have been rumored and in some cases substantiated instances of developers (Interceptor, 3D Realms, etc) brought on to create a remaster of SiN with the projects being quietly cancelled or held forever in legal limbo. In 2014 a little developer called Nightdive Studios released SiN Gold on Good Old Games.
Which brings us to today with the SiN games being pulled from Steam. No comment has been made on the matter, but the SteamDB page indicates that the titles were retired at the publisher’s request. Hopefully SiN Episodes isn’t gone for good and with luck we might get more than radio silence on the title no longer being for sale. SiN Gold is still available at the GOG link.